CBT stands for cognitive behavioural therapy and it works by looking at you how your current thoughts affect your behaviours. We all have ‘negative’ thoughts but if you have too many, or they are too unhelpful and give a distorted view of your reality, they can negatively affect how you behave in the world. For example, if you repeatedly think ‘I’m boring’ it can stop you being able to engage in conversations and build meaningful relationships. CBT is the main therapy used in the NHS, so you are likely to be recommended CBT by your GP. It can be effective for changing current patterns of thought and behaviour but doesn’t really explore issues from your past.
You can read more about CBT here:
https://www.nhs.uk/conditions/cognitive-behavioural-therapy-cbt/